Sensors can be used for monitoring and controlling in a variety of applications. Such applications may include use in automotive vehicle safety systems. Here, the sensors can be used to detect environmental changes such as collisions and trigger deployment of an airbag system in a vehicle. The triggering event initiates communication between the sensor and the electronic control unit of the vehicle. Thereby, voltage variations, such as short-term setbacks of the supply voltage, can occur in the sensor supply networks of vehicles and particularly in certain areas of the sensor supply network. For example, heavy jerky movements, such as shocks or vibrations of the vehicle, can cause short-term interruptions at one of the plug connections, so that short-term setbacks of the voltage supply of security-relevant systems, such as the airbag sensor, can also occur. These setbacks of the voltage supply are generally referred to as micro-breaks.
Micro-break protective circuitry generally utilizes one or more buffer capacitors as secondary voltage sources to maintain supply voltage in the event of momentary losses or interruptions. A conventional method used to maintain the supply voltage during the occurrence of a micro-break is to charge the buffer capacitors to the operating voltage by connecting the capacitor to the airbag sensor voltage supply. One drawback of this method is that a reduction in the operating voltage decreases the amount of charge available to the buffer capacitor, thereby inhibiting the ability of the capacitor to shunt the micro-break.
Another conventional approach for overcoming this drawback is to utilize synchronization pulses to provide an increased charging voltage to the buffer capacitor. With this method, short periodic pulses are applied to the input terminals of an airbag sensor to create an increased supply voltage at the input. As a result, this allows the buffer capacitor to store a greater charge and discharge a higher voltage than the operating voltage in the event of a micro-break. A drawback to this approach is that newer protocols which utilize synchronization pulses decrease the value of the supply voltage by applying negative synchronization pulses, which in turn fail to provide the necessary charging voltage to the buffer capacitor.